title: Effects of low-dose microwave on healing of fractures with titanium alloy internal fixation: an experimental study in a rabbit model.
abstract: BACKGROUND
  Microwave is a method for improving fracture repair. However, one of the contraindications for microwave treatment listed in the literature is surgically implanted metal plates in the treatment field. The reason is that the reflection of electromagnetic waves and the eddy current stimulated by microwave would increase the temperature of magnetic implants and cause heat damage in tissues. Comparing with traditional medical stainless steel, titanium alloy is a kind of medical implants with low magnetic permeability and electric conductivity. But the effects of microwave treatment on fracture with titanium alloy internal fixation in vivo were not reported. The aim of this article was to evaluate the security and effects of microwave on healing of a fracture with titanium alloy internal fixation.
  
  
  METHODS
  Titanium alloy internal fixation systems were implanted in New Zealand rabbits with a 3.0 mm bone defect in the middle of femur. We applied a 30-day microwave treatment (2,450MHz, 25W, 10 min per day) to the fracture 3 days after operation. Temperature changes of muscle tissues around implants were measured during the irradiation. Normalized radiographic density of the fracture gap was measured on the 10th day and 30th day of the microwave treatment. All of the animals were killed after 10 and 30 days microwave treatment with histologic and histomorphometric examinations performed on the harvested tissues.
  
  
  RESULTS
  The temperatures did not increase significantly in animals with titanium alloy implants. The security of microwave treatment was also supported by histology of muscles, nerve and bone around the implants. Radiographic assessment, histologic and histomorphometric examinations revealed significant improvement in the healing bone.
  
  
  CONCLUSIONS
  Our results suggest that, in the healing of fracture with titanium alloy internal fixation, a low dose of microwave treatment may be a promising method.
authors.affiliation: Department of Rehabilitation, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Ye
authors.forename: Yiming
authors.initials: Y
authors.lastname: Xu
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Tengfei
authors.initials: T
authors.lastname: Fu
authors.forename: Lan
authors.initials: L
authors.lastname: Jiang
authors.forename: Yuehong
authors.initials: Y
authors.lastname: Bai
mesh_terms: D000497:Alloys / Q000627:therapeutic use*; D000818:Animals; D001860:Bone Plates; D001842:Bone and Bones / Q000503:physiopathology; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods*; D050723:Fractures, Bone / Q000628:therapy*; D008297:Male; D008872:Microwaves; D011817:Rabbits; D013193:Stainless Steel / Q000009:adverse effects; D013696:Temperature; D014025:Titanium / Q000627:therapeutic use*; D014945:Wound Healing / Q000502:physiology
chemical_list: D000497:Alloys; D013193:Stainless Steel; D014025:Titanium